Semiconductor device with non-volatile memory cell and manufacturing method thereof

ABSTRACT

A manufacturing method of a semiconductor device, includes providing a substrate; forming a stacked gate, including a floating gate and a control gate, on the substrate; forming a stacked gate by a deposition of a select gate conductive layer on the stacked gate; forming a trench in the stacked gate by etching the stacked gate to separate a first select gate pattern and a second select gate pattern; and forming a first select gate, a second select gate, a first transistor, and a second transistor simultaneously through an etch-back process of the stacked gate

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0059550 filed on May 7, 2021, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference for all purposes.

BACKGROUND 1. Field

The following disclosure relates to a semiconductor device including non-volatile memory cell and manufacturing method thereof.

2. Description of Related Art

A non-volatile memory device is used in various application fields such as Controller IC, RFID (Radio Frequency Identification) Tag, MCU (Microcontroller Unit), Touch, etc., because data saved in a memory cell are not lost even if power is down, and it is growing in importance. Typical semiconductor devices, including non-volatile memory cells, are FLASH memory devices and EEPROMs (Electrical Erasable Programmable Read Only Memory).

In a manufacturing method of a semiconductor device, including a traditional flash memory cell, a mask is used when forming an access transistor to prevent cell leakage, leading to a feature difference between a left cell and a right. Due to mismatching caused by such feature differences, there is a limit in shrinking the minimum gate length of an access transistor.

Moreover, in manufacturing a semiconductor device, including a traditional flash memory cell, a photo resistor has to be thick in the case of etching a floating gate polysilicon, ONO (Oxide/Nitride/Oxide) layer, control gate polysilicon, etc. using a photo resistor. Furthermore, because a thick photo resistor had to be used, there is also difficulty shrinking the space between polysilicon layers of the floating gate.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

In one general aspect, a manufacturing method of a semiconductor device, includes providing a substrate; forming a stacked gate, including a floating gate and a control gate, on the substrate; forming a stacked gate by a deposition of a select gate conductive layer on the stacked gate; forming a trench in the stacked gate by etching the stacked gate to separate a first select gate pattern and a second select gate pattern; and forming a first select gate, a second select gate, a first transistor, and a second transistor simultaneously through an etch-back process of the stacked gate.

The providing of the substrate may include forming a deep N-type well region in the substrate, forming a P-type well region on the deep N-type well region, and forming a thin gate insulating layer on the P-type well region.

The trench may be formed by forming a mask pattern on the select gate conductive layer, exposing the stacked gate by etching a portion of the select gate conductive layer that is formed at an upper side of the stacked gate, using the mask pattern, and etching the exposed stacked gate.

The manufacturing method may further include forming a first insulating film spacer and a second insulating film spacer on each of a side wall of the first transistor and a side wall of the second transistor, forming drain regions under the first insulating film spacer and the second insulating film spacer, forming source regions between the first transistor and the second select gate, and forming silicide layers on the substrate, the first transistor, and the second transistor.

The manufacturing method may further include forming an etch stop layer on the silicide, forming an inter-layer insulating film on the etch stop layer, forming contact plugs connected to the drain region and the source region by etching the inter-layer insulating film using the etch stop layer, and forming metal wirings connected to the contact plug.

The stacked gate may further include a dielectric layer between the floating gate and the control gate.

The dielectric layer may be exposed through the trench.

The floating gate may be exposed through the trench.

The manufacturing method may further include a first split gate and the second split gate may be formed by etching the floating gate exposed through the etch-back process.

A height of each of the first select gate and the second select gate may be lower than maximum height of the control gate with respect to a surface of the substrate, and the first select gate and the second select gate may be respectively formed as a spacer at one side of each of the first transistor and the second transistor.

In another general aspect, a manufacturing method of a semiconductor device, includes providing a substrate; forming a stacked gate, comprising a floating gate and a control gate, on the substrate; depositing a select gate conductive layer on the stacked gate; forming a first stack pattern and a second stack pattern by etching an intermediate portion of the select gate conductive layer and the stacked gate; and simultaneously forming a first select gate and a second select gate by an etch-back process of the select gate conductive layer remaining in the stacked gate. A first transistor and a second transistor are formed between the first and the second select gate.

The first stack pattern and the second stack pattern may be formed on the floating gate conductive layer.

The forming of the stacked gate may include forming the floating gate on the substrate; forming a dielectric layer on the floating gate conductive layer; forming the control gate on the dielectric layer; depositing an a hard mask layer on the control gate; and forming the stacked gate by patterning the insulating film for the hard mask, the control gate, the dielectric layer, and the floating gate conductive layer.

A portion of the select gate conductive layer deposited at an upper side of the stacked gate may be etched to expose an intermediate portion of the stacked gate. A portion of the select gate conductive layer may remain at a side and an upper side of the stacked gate during formation of a first stack pattern and a second stack pattern by the etching of the intermediate portion of the stacked gate.

The select gate conductive layer remaining at opposite sides and an upper side of the stacked gate may be etched through the etch-back process, and the first select gate and the second select gate may be formed as spacers at a side of the first transistor and a side of the second transistor, respectively.

The manufacturing method may further include forming drain regions between the first stacked gate and the second stacked gate, and forming a first source region and a second source region below the first select gate and the second select gate, respectively.

In another general aspect, a semiconductor device includes a substrate; stacked gates, each comprising a floating gate and a control gate, disposed on the substrate; select gates, each disposed on opposing sides of adjacent ones of the stacked gates; and contact plugs, each disposed between the adjacent ones of the stacked gates. The select gates are symmetrically formed and disposed about the contact plugs.

The semiconductor device may further include a deep N-type well region disposed in the substrate, a P-type well region disposed on the deep N-type well region, and thin gate insulating layers disposed between the floating gate and the P-type well region.

The semiconductor device may further include a first insulating film spacer and a second insulating film spacer disposed on a sidewall of the transistors; drain regions, each disposed under the first insulating film spacer and the second insulating film spacer; and source regions disposed between the adjacent ones of the stacked gates.

Each of the stacked gates may further include a dielectric layer between the floating gate and the control gate.

Other features and aspects will be apparent from the following detailed description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a semiconductor device, including non-volatile memory cells according to an embodiment of the disclosure.

FIG. 2A to FIG. 10B are diagrams of a manufacturing method of a semiconductor device including non-volatile memory cell according to an embodiment of the disclosure.

Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. Drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience.

DETAILED DESCRIPTION

The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent after an understanding of the disclosure of this application. For example, the sequences of operations described herein are merely examples, and are not limited to those set forth herein, but may be changed as will be apparent after an understanding of the disclosure of this application, with the exception of operations necessarily occurring in a certain order. Also, descriptions of features that are known in the art may be omitted for increased clarity and conciseness.

The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many possible ways of implementing the methods, apparatuses, and/or systems described herein that will be apparent after an understanding of the disclosure of this application.

Throughout the specification, when an element, such as a layer, region, or substrate, is described as being “on,” “connected to,” or “coupled to” another element, it may be directly “on,” “connected to,” or “coupled to” the other element, or there may be one or more other elements intervening therebetween. In contrast, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to” another element, there can be no other elements intervening therebetween.

As used herein, the term “and/or” includes any one and any combination of any two or more of the associated listed items.

Although terms such as “first,” “second,” and “third” may be used herein to describe various members, components, regions, layers, or sections, these members, components, regions, layers, or sections are not to be limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or section from another member, component, region, layer, or section. Thus, a first member, component, region, layer, or section referred to in examples described herein may also be referred to as a second member, component, region, layer, or section without departing from the teachings of the examples.

Spatially relative terms such as “above,” “upper,” “below,” and “lower” may be used herein for ease of description to describe one element's relationship to another element as shown in the figures. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as being “above” or “upper” relative to another element will then be “below” or “lower” relative to the other element. Thus, the term “above” encompasses both the above and below orientations depending on the spatial orientation of the device. The device may also be oriented in other ways (for example, rotated 90 degrees or at other orientations), and the spatially relative terms used herein are to be interpreted accordingly.

The terminology used herein is for describing various examples only, and is not to be used to limit the disclosure. The articles “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “includes,” and “has” specify the presence of stated features, numbers, operations, members, elements, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, members, elements, and/or combinations thereof.

Due to manufacturing techniques and/or tolerances, variations of the shapes shown in the drawings may occur. Thus, the examples described herein are not limited to the specific shapes shown in the drawings, but include changes in shape that occur during manufacturing.

Herein, it is noted that use of the term “may” with respect to an example or embodiment, e.g., as to what an example or embodiment may include or implement, means that at least one example or embodiment exists where such a feature is included or implemented while all examples and embodiments are not limited thereto.

The features of the examples described herein may be combined in various ways, as will be apparent after an understanding of the disclosure of this application. Further, although the examples described herein have a variety of configurations, other configurations are possible, as will be apparent after an understanding of the disclosure of this application.

The disclosure is to solve the above problems, providing a manufacturing method of a semiconductor device including a flash memory cell that is easy to shrink an access transistor, by symmetrically forming a gate polysilicon of each access transistor, and providing a semiconductor device including non-volatile memory cell according to the method.

A targeted problem of the disclosure is not limited by the problems mentioned above. A person skilled in the relevant field of technology may understand other problems from the following description.

A detailed description of the disclosure is given below, according to the attached drawings.

FIG. 1 is a cross-sectional view of a semiconductor device, including a non-volatile memory cell, according to an embodiment of the disclosure.

With reference to FIG. 1, a semiconductor device 100 including non-volatile memory cell, according to an embodiment of the disclosure, may include a plurality of transistors 50 a, 50 b, 50 c and 50 d on a substrate 101 where a P-type well region 110 and a deep N-type well region 120 are placed.

Herein, each of the transistors 50 a, 50 b, 50 c and 50 d may include a thin gate insulating layer 140 a, 140 b, 140 c, 140 d, a floating gate 200 a, 200 b, 200 c and 200 d, a dielectric layer 300 a, 300 b, 300 c and 300 d, a control gate 400 a, 400 b, 400 c and 400 d, a thick gate insulating layer 600 and a select gate 700 a, 700 b, 700 c and 700 d.

The thin gate insulating layer 140 a, 140 b, 140 c, 140 d, the floating gate 200 a, 200 b, 200 c and 200 d, the dielectric layer 300 a, 300 b, 300 c and 300 d, and the control gate 400 a, 400 b, 400 c and 400 d are stacked together. The stacked structure may be called as a stacked gate. The stacked gate may comprise at least the floating gate 200 a, 200 b, 200 c and 200 d, the dielectric layer 300 a, 300 b, 300 c and 300 d, and the control gate 400 a, 400 b, 400 c and 400 d.

Select gates 700 a, 700 b, 700 c and 700 d, each is disposed on opposing sides of adjacent ones of the stacked gates. Select gates 700 a, 700 b, 700 c and 700 d are respectively formed in the transistors 50 a, 50 b, 50 c and 50 d. For example, a first select gate 700 a is formed on sidewalls of a first floating gate 200 a and a first control gate 400 b. A second select gate 700 b is formed on sidewalls of a second floating gate 200 b and a second control gate 400 b.

Dielectric layers 300 a, 300 b, 300 c, 300 d may comprise a silicon nitride layer or an ONO (Oxide/Nitride/Oxide) layer. Thin gate insulating layers 140 a, 140 b, 140 c, 140 d may be formed between a floating gate 200 a, 200 b, 200 c and 200 d and a substrate 101. Thick gate insulating layers 600 may be formed between the select gate 700 a, 700 b, 700 c and 700 d and a substrate 101. A deep N-type well region 120, a P-type well region 110, and shallow trench isolations(STI) 130 may be formed in a substrate 101.

Source regions 150 a, 150 b and 150 c may be formed adjacent to the select gates 700 a, 700 b, 700 c and 700 d. Additionally, common drain regions 160 a and 160 b may be formed between the thin gate insulating layers 140 a, 140 b, 140 c and 140 d. Lightly doped drain (LDD) regions 910 may be formed in the source regions 150 a, 150 b and 150 c and the drain regions 160 a and 160 b. Spacers 920 and 930 may be formed on the source regions 150 and the drain regions 160 a and 160 b. Silicide layers 940 may be formed on the control gates 400, the source regions 150 and the drain regions 160. An etch stop layer 950 and an inter-layer insulating film 960 may be formed on the transistors 50 a, 50 b, 50 c and 50 d. A plurality of contact plugs 970 are electrically connected with the drain regions 160 a and 160 b and the source regions 150 a, 150 b and 150 c. A plurality of metal wirings 980 are electrically connected to a plurality of contact plugs 970.

When forming the select gates 700 a, 700 b, 700 c and 700 d for access transistors, the select gates 700 a, 700 b, 700 c and 700 d are symmetrically formed with the same length because an etch-back process is performed without a mask. Thus, with a semiconductor device including a non-volatile memory cell, according to an embodiment of the disclosure, it is easier to shrink an access transistor because each of the select gates 700 a, 700 b, 700 c and 700 d for access transistors is symmetrically formed with the same length, and electrical performance may be substantially identical.

The description below describes a process for a manufacturing method of a semiconductor device, including a non-volatile memory cell according to an embodiment of the disclosure in further detail.

FIG. 2A to FIG. 10B are diagrams of a manufacturing method of a semiconductor device, including a non-volatile memory cell according to an embodiment of the disclosure.

FIG. 2A describes an operation of providing a substrate and forming a stacked gate layer, including a floating gate and a control gate on the substrate.

An operation of providing a substrate may include forming a deep N-type well region 120 in a substrate 101, forming a P-type well region 110 on the deep N-type well region 120, and forming a plurality of STI (Shallow trench isolation) 130 in the substrate 101.

Herein, the substrate 101 may include a semiconductor material. It may be a silicon (Si) substrate, gallium-arsenic (GaAs) substrate, indium phosphide (InP) substrate, germanium (Ge) substrate, or silicon germanium (SiGe) substrate. In an embodiment, the substrate 101 may be doped and have conductivity and doped by an N-type or P-type dopant. Further, the substrate 101 may include a well region doped by an N-type or P-type dopant inside the substrate. Herein, the STI (Shallow trench isolation) 130 may be formed as an isolation insulating layer at opposite ends on the substrate 101.

Additionally, forming a stacked gate layer 10, including a floating gate conductive layer 200 and a control gate conductive layer 400 on the substrate may involve the following operations: forming a thin gate insulating layer 140 on the substrate 101; and depositing a floating gate conductive layer 200, a dielectric layer 300, a control gate conductive layer 400, and a hard mask layer 500 in order. A dielectric layer 300 may be an insulating film that forms a silicon oxide layer, a silicon nitride layer, and a silicon oxide layer in order.

Thus, a stacked gate layer 10 formed on a substrate 101 may include a thin gate insulating layer 140, a floating gate conductive layer 200, a dielectric layer 300, a control gate conductive layer 400, and a hard mask layer 500. A stacked gate layer 10 may be patterned using a photoresist pattern (PR) 550 formed in the stacked gate layer 10. Herein, a floating gate conductive layer 200 and a control gate conductive layer 400 may be formed using polysilicon.

FIG. 2B describes a formation of a stacked gate on the substrate, including a floating gate and a control gate.

First and second stacked gates 10 x and 10 y may be formed by etching a stacked gate layer 10 with a photoresist pattern(PR) 550 used as a mask. Each stacked gate 10 x and 10 y may respectively include a thin gate insulating layer 140, a floating gate 200, a dielectric layer 300, a control gate 400, and a hard mask layer 500. The rest of the photoresist pattern (PR) 550 that remains after etching may be removed through plasma ashing.

FIG. 3 describes an operation of forming a thick gate insulating layer on the stacked gate.

FIG. 3 shows that a thick gate insulating layer 600 is formed on the first and second stacked gates 10 x and 10 y. Herein, it may be desirable to form the thick gate insulating layer 600 through thermal oxidation or CVD method, but it is not limited thereto. The thick gate insulating layer 600 is used as a select gate insulating layer.

FIG. 4 describes a formation of a stacked gate where the floating gate conductive layer, the control gate, and the select gate conductive layer stacked on the substrate by depositing the select gate conductive layer on the stacked gate.

With reference to FIG. 4, a single select gate conductive layer 650 may be formed on the thick gate insulating layer 600. A single select gate conductive layer 650 may be formed using a polysilicon material by CVD. Herein, by depositing a select gate conductive layer 650 on a first and second stacked gate 10 x and 10 y, a first stacked gate 10 x and a second stacked gate 10 y may be respectively formed. Each of the first stacked gate 10 x and the second stacked gate 10 y may comprise a thin gate insulating layer 140, a floating gate 200, a dielectric layer 300, a control gate 400, a hard mask layer 500, a thick gate insulating layer 600, and a select gate conductive layer 650.

FIG. 5 describes a photolithography stage to form a trench by etching a stacked gate.

With reference to FIG. 5, a photoresist pattern 800 may be formed in the stacked gates 10 x and 10 y. That is, a photoresist pattern 800 may be formed on the select gate conductive layer 650. The photoresist pattern 800 is used as a mask to form a trench in each of the stacked gates 10 x and 10 y.

FIGS. 6A and 6B describe performing a first etching the select gate conductive layer and the control gate to form a trench in the stacked gate.

Depending on the etching conditions, the first etching may be FIG. 6A or FIG. 6B. Different etch stop points are shown in FIGS. 6A and 6B.

First, with reference to FIG. 6A, a select gate conductive layer 650, a thick gate insulating layer 600, a hard mask layer 500 and the control gate 400 are sequentially etched using a photoresist pattern 800. First and second trenches 850 a and 850 b may be respectively formed in the first and second stacked gates 10 x and 10 y, by etching the first and second stacked gates 10 x and 10 y. Two hard mask layers 500 are divided into four hard mask layers 500. Likewise, two control gates 400 are divided into four control gates through an etching process. The four hard mask layers 500 and four control gates 400, each side surface adjacent to the trenches 850 a and 850 b is exposed.

The first etching process may be stopped at a dielectric layer 300. The first etching process may be stopped at either of a silicon oxide layer (top), a silicon nitride layer (middle), or a silicon oxide layer (bottom) in the dielectric layer 300. Most cases, the silicon nitride layer (middle) may be used as an etch stop layer. If the etch-back process is further carried out extensively, it may be beneficial to stop forming a trench at a dielectric layer, as illustrated in FIG. 6A.

FIG. 6B shows another example for forming a trench. With reference to FIG. 6B, etching may be stopped at a floating gate 200 when forming trenches 870 a and 870 b. The rest of the parts are similar to FIG. 6A. If the etch-back process is further carried out lightly, it may be beneficial to stop etching at a floating gate 200.

FIGS. 7A and 7B show the removal of photoresist pattern.

FIGS. 7A and 7B show that a plurality of the patterned conductive layers 650 a, 650 b and 650 c may be formed, and they are separated by the trenches 850 a and 850 b. For example, at least three patterned conductive layers 650 a, 650 b and 650 c, are remained at a side and an upper side of the first and second stacked gates 10 x and 10 y. A second patterned conductive layer 650 b is formed across the first and second stacked gates 10 x and 10 y. First and third patterned conductive layers 650 a and 650 c are formed on the first and second stacked gates 10 x and 10 y, respectively. The remained three patterned conductive layers 650 a, 650 b and 650 c may be converted into separated select gates 700 a, 700 b, 700 c and 700 d by the etch-back process (See FIG. 8). An additional etching process, such as the etch-back process, may be needed to form a select gate as a spacer shape.

FIG. 8 illustrates performing an etch-back process on the remaining select gate conductive layer and the floating gate to separate the stacked gate, thereby simultaneously forming a plurality of transistors.

With reference to FIG. 8, in a method of the disclosure of manufacturing a semiconductor device including a flash memory cell, an etch-back process may be carried out. In a method of the disclosure of manufacturing a semiconductor device including a flash memory cell, select gates 700 a, 700 b, 700 c and 700 d may be formed from the three patterned conductive layers 650 a, 650 b and 650 c by executing a blanket etch-back process. For example, the first patterned conductive layer 650 a is converted into a first select gate 700 a. Likewise, the second patterned conductive layer 650 b is divided into a second select gate 700 b and a third select gate 700 c by the etch-back process. Further, the third patterned conductive layer 650 c is converted into a fourth select gate 700 d. A height of each of the first select gate 700 a and the second select gate 700 b is lower than maximum height of each of the control gates 400 with respect to a top surface of the substrate 101.

Select gates 700 a, 700 b, 700 c and 700 d may be formed as a spacer at a sidewall of a transistor 50 a-50 d. Depending on the conditions of the etch-back process, select gates 700 a, 700 b, 700 c and 700 d formed at a sidewall of the transistor 50 a-50 d may be designed with appropriate thickness and structure. During the etch-back process, the thin gate insulating layer 140 plays a role of an etch stop layer. Thus, the thin gate insulating layer 140 may be remained on a top surface of the substrate 101 (not shown). Further, a cleaning process may be additionally performed to remove polysilicon residues, which are byproducts of the etch-back process. The cleaning process may also remove the remaining thin gate insulating layer 140, so the top surface of the substrate 101 may be exposed.

Moreover, in a method of the disclosure manufacturing a semiconductor device including a flash memory cell, an etch-back process is executed without a mask when forming an access transistor. Thus, select gates 700 a, 700 b, 700 c and 700 d for access transistors may be symmetrically formed with the same length.

A dielectric layer 300 or a floating gate 200 that remains in a stacked gate 10 x and 10 y may be etched through an etch-back process. Herein, with a formation of trench 850 by etching a dielectric layer 300 and a floating gate 200, a thin gate insulating layer 140 may be exposed.

Eventually, select gates 700 a, 700 b, 700 c and 700 d and 4 transistors 50 a, 50 b, 50 c and 50 d may be formed simultaneously from the two stacked gates 10 x and 10 y. Herein, a transistor 50 a, 50 b, 50 c and 50 d may include a floating gate electrode (FG, 200), a dielectric layer 300, and a control gate electrode (CG, 400).

FIG. 9A shows an operation of forming lightly doped drain (LDD) regions in a substrate.

With reference to FIG. 9A, ion implantation may be executed to form LDD regions 910 in a substrate 101.

FIG. 9B describes the formation of an insulating film spacer at a sidewall of a transistor.

With reference to FIG. 9B, a first insulating film spacer 920 and a second insulating film spacer 930 may be formed at a sidewall of a transistor 50 a-50 d. A silicon oxide layer 920 and a silicon nitride layer 930 may be used as a material of spacers 920 and 930. In forming the spacers 920 and 930, a hard mask layer 500 may be removed, and a top surface of the control gate electrode 400 may be exposed.

As shown in FIG. 9B, a thin gate insulating layer 140, a floating gate(FG) 200, a dielectric layer 300 and a control gate(CG) 400 directly contact both the thick gate insulating layer 600 and the first insulating film spacer 920. Select gates are formed on the thick gate insulating layer 600, and the second insulating film spacer 930 is formed on the first insulating film spacer 920.

Further, source regions 150 a, 150 b and 150 c and drain regions 160 a and 160 b may be formed through ion implantation in the P-type well region after the etch-back process. The source regions 150 a, 150 b and 150 c, and the drain regions 160 a and 160 b may be a region of a substrate doped as N-type or P-type. In case a substrate is doped as N-type or P-type, the source regions 150 a, 150 b and 150 c and the drain regions 160 a and 160 b may be a region doped as a dopant that is opposite to a type of a substrate, but it is not limited thereto. The source regions 150 a, 150 b and 150 c are formed adjacent to the select gates 700 a, 700 b, 700 c and 700 d. Drain regions 160 a and 160 b, each is disposed under the first insulating film spacer 920 and the second insulating film spacer 930.

FIG. 9C illustrates an operation of forming silicide layers on the substrate.

With reference to FIG. 9C, in a method of the disclosure manufacturing a semiconductor device including a flash memory cell, silicide layers 940 may be formed on the source regions 150 a, 150 b and 150 c, and the drain regions 160 a and 160 b. Another silicide layers 940 are also formed on the control gates 400 of the first to fourth transistor 50 a-50 d.

FIG. 10A illustrates a formation operation of an etch stop layer and an inter-layer insulating film 960.

As shown in FIG. 10A, a thin etch stop layer 950 is formed on the substrate 101. The etch stop layer 950 directly contacts the silicide layers 940 and the second insulating film spacer 930. The thin etch stop layer 950 may be selected from one of a SiON, SiN or SiO2. The etch stop layer 950 is used for borderless contact(BLC) hole, wherein a contact plug is formed in the borderless contact(BLC) hole. Additionally, a thick inter-layer insulating film 960 is formed on the etch stop layer 950.

FIG. 10B shows an operation of forming contact plugs 970 that are electrically connected to the drain regions 160 and the source regions 150 through etching the inter-layer insulating film 960, using the etch stop layer 950; and metal wirings 980 that are electrically connected to the contact plugs 970.

According to the disclosure, the gate polysilicon of each access transistor is symmetrically formed by an improved process, making it significantly easier to shrink an access transistor.

Meanwhile, this specification additionally discloses a semiconductor device, including a non-volatile memory cell, produced by the manufacturing method of a semiconductor device, including a flash memory cell.

A semiconductor device 100 including a non-volatile memory cell, produced by the manufacturing method of a semiconductor device including a flash memory cell, may include consistently spaced a plurality of transistors 50 a, 50 b, 50 c and 50 d on a substrate 101 where a P-type well region 110 and a deep N-type well region 120 are placed. Select gates 700 a, 700 b, 700 c and 700 d for access transistors may be symmetrically formed with the same length. Herein, the transistor may include a floating gate 200, a dielectric layer 300, and a control gate 400.

Herein, because an etch-back process is executed without a mask when forming an access transistor, select gates 700 a, 700 b, 700 c and 700 d for access transistors may be symmetrically formed with the same length.

Thus, as a semiconductor device 100 including a non-volatile memory cell, engineered by the manufacturing method of a semiconductor device including a flash memory cell has select gates 700 a, 700 b, 700 c and 700 d for access transistors that are symmetrically formed with the same length, electrical performance is identical and allows for an easier shrinking of an access transistor.

According to the manufacturing method of a semiconductor device, including a flash memory cell, gate polysilicon of each access transistor is symmetrically formed by an improved process, allowing for an easier shrinking of an access transistor.

While this disclosure includes specific examples, it will be apparent after an understanding of the disclosure of this application that various changes in form and details may be made in these examples without departing from the spirit and scope of the claims and their equivalents. The examples described herein are to be considered in a descriptive sense only, and not for purposes of limitation. Descriptions of features or aspects in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if the described techniques are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined in a different manner, and/or replaced or supplemented by other components or their equivalents. Therefore, the scope of the disclosure is defined not by the detailed description, but by the claims and their equivalents, and all variations within the scope of the claims and their equivalents are to be construed as being included in the disclosure. 

What is claimed is:
 1. A manufacturing method of a semiconductor device, comprising: providing a substrate; forming a stacked gate, comprising a floating gate and a control gate, on the substrate; forming a select gate conductive layer on the stacked gate; performing a first etching the select gate conductive layer and the control gate to form a trench in the stacked gate; and performing an etch-back process on the remaining select gate conductive layer and the floating gate to separate the stacked gate, thereby simultaneously forming a first transistor and a second transistor, wherein the first transistor comprises: a first floating gate formed on the substrate; a first control gate formed on the first floating gate; and a first select gate formed on sidewalls of the first floating gate and the first control gate, and wherein the second transistor comprises: a second floating gate formed on the substrate; a second control gate formed on the second floating gate; and a second select gate formed on sidewalls of the second floating gate and the second control gate.
 2. The manufacturing method of claim 1, wherein the providing of the substrate includes forming a deep N-type well region in the substrate, and forming a P-type well region on the deep N-type well region.
 3. The manufacturing method of claim 1, wherein the performing a first etching the select gate conductive layer and the control gate to form a trench in the stacked gate comprises; forming a mask pattern on the select gate conductive layer; exposing the stacked gate by etching a portion of the select gate conductive layer that is formed at an upper side of the stacked gate, using the mask pattern; and etching the exposed stacked gate.
 4. The manufacturing method of claim 1, wherein the first transistor further comprises: a first thin gate insulating layer formed below the first floating gate; a first thick gate insulating layer formed below the first control gate; and a first dielectric layer formed between the first floating gate and the first control gate, and wherein the second transistor further comprises: a second thin gate insulating layer formed below the second floating gate; a second thick gate insulating layer formed below the second control gate; and a second dielectric layer formed between the second floating gate and the second control gate.
 5. The manufacturing method of claim 4, further comprising: forming a common drain region between the first thin gate insulating layer and the second thin gate insulating layer; and forming a first source region and a second source region adjacent to the first and second thick gate insulating layers, respectively.
 6. The manufacturing method of claim 5, further comprising: forming silicide layers on the common drain region, the first source region and the second source region; forming an etch stop layer on the silicide layers; forming an inter-layer insulating film on the etch stop layer; forming contact plugs connected to the drain region, the first and second source regions by etching the inter-layer insulating film using the etch stop layer; and forming metal wirings connected to the contact plugs.
 7. The manufacturing method of claim 4, wherein each of the first and second dielectric layers comprises a first oxide layer, a second nitride layer and a third oxide layer, wherein the first etching stops on the second nitride layer.
 8. The manufacturing method of claim 1, wherein a height of each of the first select gate and the second select gate is lower than maximum height of each of the first control gate and the second control gate with respect to a surface of the substrate.
 9. The manufacturing method of claim 1, wherein the forming a stacked gate comprises: forming a floating gate conductive layer on the substrate; forming a dielectric layer on the floating gate conductive layer; forming a control gate conductive layer on the dielectric layer; and patterning the control gate conductive layer, the dielectric layer, and the floating gate conductive layer.
 10. The manufacturing method of claim 3, wherein the select gate conductive layer remaining at opposite sides and an upper side of the stacked gate is etched through the etch-back process.
 11. A semiconductor device, comprising: a substrate; stacked gates, each comprising a floating gate and a control gate, disposed on the substrate; select gates, each disposed on opposing sides of adjacent ones of the stacked gates; and contact plugs, each disposed between the adjacent ones of the stacked gates, wherein the select gates are symmetrically formed and disposed about the contact plugs.
 12. The semiconductor device of claim 11, further comprising: a deep N-type well region disposed in the substrate; a P-type well region disposed on the deep N-type well region; and thin gate insulating layers disposed between the floating gate and the P-type well region.
 13. The semiconductor device of claim 11, further comprising: a first insulating film spacer and a second insulating film spacer disposed on a sidewall of the stacked gates; drain regions, each disposed under the first insulating film spacer and the second insulating film spacer; and source regions disposed between the adjacent ones of the stacked gates.
 14. The semiconductor device of claim 11, wherein each of the stacked gates further includes a dielectric layer between the floating gate and the control gate. 